vE. GRISSINGER. f TELBBHONB RECEIVER, APPLICATION FILED NOV. 18, 1911. Patented Feb. 23, 1915. 2. SHEETS-SHEET 1. Lmmow.. . momtoz 91,5042 ma am. . A WMQOM S E. GRISSINGER.. 4 TELEPHONE RECEIVER. APPLICATION FILED NOV. 18, 191`1- 19129908?, l Patented Feb. 23, 1915. 2 SHEETS-SHEET 2. K- ln/ @anni f ri viga ici iti in@ er ith i dit meanest.. Application filed November: 3.5, 1913i. following is a fuli, clear, and exact description thereof. hily invention reiates to an improven'ient in telephone receivers7 in which (a) the vibratory portions of the instruments are so arranged that the forces which are brought to hear upon them are balanced in everv direction, and so that as a consequence there is a permanency of adjustment; (b) the natura] period of vibration of the moving parts is raised lto a pitch beyond the range of vibration of dominant voice sounds, thus eliminating the effects of resonance; damping in the ordinarily accepted form is not employed; ((Z) the mass of the vihratory portions is reduced as much as possible so that the instrunients are sensitive and powerful; and7 (c) the reduction of mass ofA the moving parts, absence of damping, high fundamental frequencyand method of supT porting armatures upon a sensitive suspension is such that a more nearly perfect transformation of the telephone current waves into sound waves is effected. The receiver which constitutes an embodiment of my invention is built up of the equivalent of a double watch case receiver, the permanent magnets with their pole pieces heing placed hack to hack. rthe usual telephone receiver is deficient in power hecause of the low initial force of attraction between the magnets and the diaphragm. rthis cannot he increased without increasing the mass of the diaphragm and an increase of diaphragm mass imposes conditions which make for other imperfections in operation. The usual diaphragm of small mass and low capacity for magnetic lines of force, as well as the larger diaphragms of greater mass, give an imperfect transformation from current waves into sound waves, principally because of their factor. mpenfect transformations of complex telephone current waves also result because of the fact that all waves are not transformed with the same relative degree of volume. Telephone receivers constructed in accorciance with the principles herein described Specification. of Letters Eatc-nt. TQSOTIRDCG Serial Nt. 680,993. correct for the effects of resonance, transform all waves with the saine relative degrees of volume and give greater power. instruments which are made in accordance with my invention avoid all of the objections :hove enumerated. f have shown one embodiment of my invention in the accompanying drawings, in which- Figure 1 indicates a vertical section of a telephone receiver made in accordance with my invention; lfig. i2 indicates a vertical section of th'ereceiver shown in Fig. 1 but taken on a plane at right angles to the plane upon which the section in Fig. 1 is taken; Fig. B is an elevation of the front cover for thereceiver casing; Fig. 1iindicates a longitudinal sectionof the armatures to beused in a slightly modified form of the instrument; Fig. 5 indicates aniodilication of my invention in which the permanent magnets may he provided with coils to increase their strength; andV Fig. G indicates a diagrammatic view of a simple form of circuit arrangement in which my receiver may he used. l In the drawings` 1 .indicates a receiver casing'having a handle 2 attached theretof'lhe handle 2 is holiow andv has an opening 3 at its lower end `to receive the end of the telea recess in the face of the cover 6 over the. opening Z by means of a ring 9 fitting in the front of the opening 7. lVithin the casing l theoperative elements of the receiver are inclosed. The type ofreceiver shown is constructed hy assembling'for each of two magnetic units a series of semieircular permanent magnets l0 for each set, to which there are attached soft iron or silicon steel pole pieces 11, which pole pieces carry exciting coils 12. The two lunits are placed hack to back and are clamped tightly together by means of screws 13 (Fig. 2) passing throughone of a pair of rings 14 and engaging in threaded apertures in' the otherring 14. Each of the rings 14 has at its lower portion a screw 15 which is screw-threaded into the face of the ring 14 and projects beyond the same where it carries a hardened steel grooved-roller 1G to support a steel piano wire 1 7.' 'The ends of the piano wire 17 extend into transverse holes 23 in tapered pins 19, which are supported. in similarly shaped openings 18 in the faces of the rings 14C. Once that the pins 19 have been adjusted to place the wire 17 lunder tension, a wedge 20 is inserted between the pins 19 to maintain them in their adjusted positions. After the tapered pins 19 'have been adjusted, the wiie 17 is put under further tension by means of four adjusting screws 21 which are carried in projections 22 up'onthe face-of the ring 14:. The adjustable-screws 21 may be constructed in any desired manner so that their inner ends bear against the wire 17. The casing 1 is provided with apertures 21'l to render the ad` `instable screws 21 accessible withoutk removing theeasing. An' armature support 23 extends from f the frontto the rear ofthe receiver casing 1`between the two pairs of poles 11, sai-d 'armature support having. screw-threaded thereto a pair of armatures 24, the faces of which extend over the ends of the pole pieces 12. A pair of, lock nuts 25 are screwed upon the armature'support V23'to maintain the armatures 24`in theiradjusted position. It is ,intended that thev lock nuts 25 shall also support upontheir outer faces the wire 17.l Beyond the wire 17 the rod 23 carries at the rearof the easing another leek nut 26, and at the front of the casing an armature type of diaphragm 27, that is -to say, a diaphragm having a free edge, Y which.occupiesa'position immediately be- Ahind the opening 7 in the ear cap. The windings 12 of thereceiver coils are preferably connected each pair in series and the two pairs together in multiple vre- 'lation through two pairs` of terminals`28 and 29. which are made a part of'a'n insu.- lating block 30, which block is attached by' screws 31 to the casing l. The receiver cord '4 passingr through the hollow yhandle 2 is attached vto the terminals 29 which are in electrical contact with the 'terminals 28. The hollowr handle 2 is attached to the block 30 by being'threaded thereon; I Instead of usingthearmature diaphragm 27 .'I may make use of the ordinary tvpe of vibratorv diaphragm, as shownv in Fig'. 4. `In this figure 32 indicates the ordinarytype of vihratory diaphragm which 'is attached to the Aend of the rod 23 by means of a pair -of nuts 33 lrcated onv opposite sides of the diaphragm 32. The diaphragm 32 is maintained in position at its periphery bv being Aclamped between the casing 1 and the ear c'ap'G or in any other suitable manner. As shown in Fig. 5, I may equip the permanent magnets`10 with special exciting .coils34- to increase their strength, which coils derive their energy from the same 'faces of the pole pieces 11'. ineens? current which passes through the trans-- mitter. The coiis 8% are preferably wound u'pon copper bobbins Bto act as a sheath so that telephone currents passing through the coils do nrt, in any case,'affect the inag netic field or the receiver. In this construction it is preferable that the coils 3-1- and 12 shall be electrically connected in series mul` i tiple relation. ` In Fig. GI have shown a. simple form of circuit arrangement in which my transmitter may be used. In this figure' Tr. indicates the transmitter, b indicates the battery of the local transmitter circuit L, p, 72 indicate the'primaries of the induction 'coillccated in said circuit, s indicates the sec- -ondary of said' induction coil which is located inthe main circuit m, said circuit also including the receiver R, and a bell B1 bridges across the main line m. The operation of thereceiver is as follows: There are two magnetic fields created site exciting coils 12 tend to lessenl the'fdegrec of attraction between their pole pieces and armature. The result is a displacement of the armatures bodily in one direction. In this manner a vibration of the armatures and the wire suspension is set up by the telephone'current waves and this. vibration is manifest in a movement of'tlie armature diaphragm 27. In the case where the diaphragm 32 of the ordinary tvpe is used, the vibrations are communicated to it instead of to the armature diaphragm 27. The supporting ofthe vibratory portion of the instrument upon the wire suspension as shown, and the extreme tension of the latter as produced bv the winding pins and the lateral deflecting members 21,'. prevents resonancefof the apparatus andprovides a more nearly perfecttransfrmation of the current variations' into mechanical vibrations of the armature. VVhileI have described my invention above in detail,`I wish it to be understood that many changes may be made therein without departing from the spiritof `the ap- .paratus I claim: 1 A telephone receiver comprising Vavibr'atory element, a` movable armature attached theretoya 4magnet for'moving. the 1,129,087 l v l tt "armature, and means for balancing the armature by means of oppositely acting forces, comprising wire supports placed under'tension by bowing. .y 2. Apparatus of the kind described com! prising an electroJrnagnet, an armature therefor and a suspension for such armature comprising a Wire, means for imparting. high initialltension thereto, bearings for said rWire intermediate of the said tension means, and a connection between thecen' rcction that is transverse to the direction of vibratry movement of the armature. K 4. Apparatus of the kind described comprising an electro-magnet subject to variation by electrical voice current, an armature therefor, two adjacent wires stretched under .high lnltlal tension across the llneof movement of the armature and secured thereto,y and means actingtransversely to such l line for deflecting the said Wires 1n their common I planev and adapted to increase thefundamental frequency thereof. 5. The combination of' an electro-magnet subject to variation-by electrical'voice current, an armature therefor, and means for imposing a high natural frequency upon the said armature comprising a Wire connected f thereto, means for holding the same .nder high initial tension, and fmeans intermediate such holding means, adapted for adjustment to deflect said 4Wire from a lstraight line and transversely to the direction of' Vibration of the armature. 6. The combination of an electro-magnet, an armature therefor and meansl for imposing a highfundamental frequency upon said armature Vand the parts vibrating therewith comprising two adjacentand substantiallyparallel Wires, means for holding the/saine under a hightension, and thrust screws acting on said Wires to deflect'them in their com'mon plane, thereby shortening `the effectivelength of. said Wires and'increasing the frequency thereof. Iny testimony that I claim the foregoing I hare hereunto set my hand. BLW-oon GRIssINGER. Witnesses: 'I y 4 DANL WJEMERLING, FRANKLIN R. 'Bnowlm



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